Assume all temperatures to be exact. A large window measures 2.1 m by 3.1 m . Pa

Question

Assume all temperatures to be exact. A large window measures 2.1 m by 3.1 m .

Part A: At what rate will heat be conducted through the window when the room temperature is 25 C and the outside temperature is 8 C if the window consists of a single pane of glass 3.8 mm thick. (Assume that there is a constant temperature difference and consider conduction only.) Answer in J/s

Part B: At what rate will heat be conducted through the window when the room temperature is 25 C and the outside temperature is 8 C if the window instead has a double pane of glass (a "thermopane"), in which each pane is 2.2 mm thick, with an intervening air space of 1.2 mm ? (Assume that there is a constant temperature difference and consider conduction only.)

Explanation / Answer

rate of heat transfer H = dQ/dt = KA(T2-T1)/L

where K = coeffficient of thermal conductivity of window is 0.8

A = area

T2-T1 = change of temperartue

dQ/dt = 0.8 * 2.1*3.1 * (25-8)/(3.8e -3)

dQ/dt = 23298.94 Watts

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rate of heat transfer H = dQ/dt = KA(T2-T1)/L

where K = coeffficient of thermal conductivity of window is 0.93

A = area

T2-T1 = change of temperartue

dQ/dt = 0.93* 2.1*3.1 * (25-8)/(3.4 e -3)

dQ/dt = 30271.5 Watts

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